package logic

import (
	"context"
	"strconv"

	"spark-server/internal/module/upload/entity"
	"spark-server/internal/pkg/errs"
	"spark-server/internal/pkg/i18n"
	"spark-server/internal/pkg/media"
	"spark-server/internal/pkg/reqctx"
	"spark-server/internal/pkg/validate"

	"go.uber.org/zap"
)

// CreateInput requests a single-object Presigned PUT. The client does not choose the key.
type CreateInput struct {
	Purpose string `json:"purpose" validate:"required" label:"field.purpose" errmsg:"required:validate.upload.purpose_required"`
	Mime    string `json:"mime" validate:"required,max=128" label:"field.mime" errmsg:"required:validate.upload.mime_required;max:validate.upload.mime_invalid"`
	Size    int64  `json:"size" validate:"required,gt=0" label:"field.size" errmsg:"required:validate.upload.size_required;gt:validate.upload.size_invalid"`
	GroupID int64  `json:"group_id" validate:"omitempty,gt=0" label:"field.group_id"`
}

func (s *Service) CreateCredential(ctx context.Context, userID int64, in *CreateInput) (*entity.Credential, error) {
	if !s.ready() {
		return nil, errs.ErrAvailable
	}
	if userID <= 0 {
		return nil, errs.ErrUnauthorized
	}
	if in == nil {
		return nil, errs.ErrInvalidArgument
	}
	if err := validate.StructLang(reqctx.Lang(ctx), in); err != nil {
		return nil, err
	}
	if !s.allow(userID) {
		return nil, errs.ErrRateLimited
	}
	return s.issuePut(ctx, userID, in)
}

func (s *Service) issuePut(ctx context.Context, userID int64, in *CreateInput) (*entity.Credential, error) {
	_, mime, err := matchSpec(ctx, in)
	if err != nil {
		return nil, err
	}
	if err := s.checkDeclaredSize(ctx, in.Purpose, in.Size); err != nil {
		return nil, err
	}
	name := reqctx.NewObjectName()
	ownerID := userID
	if in.Purpose == entity.PurposeGroupAvatar {
		if err := s.readyGroupAvatar(ctx, userID, in.GroupID); err != nil {
			return nil, err
		}
		ownerID = in.GroupID
	}
	key := entity.BuildObjectKey(in.Purpose, ownerID, name, dayOf(s.now()), entity.ExtForMIME(mime))
	url, err := s.store.PresignPut(ctx, key, mime, in.Size, s.ttl)
	if err != nil {
		return nil, err
	}
	return &entity.Credential{
		ObjectKey: key,
		UploadURL: url,
		Method:    entity.MethodPUT,
		Headers: map[string]string{
			"Content-Type":   mime,
			"Content-Length": strconv.FormatInt(in.Size, 10),
			"If-None-Match":  "*",
		},
		ExpiresIn: s.expiresIn(),
	}, nil
}

// checkDeclaredSize applies soft media policy on credential size (no dimensions at this stage).
func (s *Service) checkDeclaredSize(ctx context.Context, purpose string, size int64) error {
	if s == nil || !s.media.Enabled {
		return nil
	}
	var v *media.Violation
	switch purpose {
	case entity.PurposeAvatar, entity.PurposeGroupAvatar, entity.PurposeMomentCover:
		v = s.media.CheckAvatarMeta(0, 0, size)
	case entity.PurposeChatVideo, entity.PurposeMomentVideo, entity.PurposeSquareVideo:
		v = s.media.CheckVideoMeta(0, 0, size, 0)
	case entity.PurposeChatImage, entity.PurposeMomentImage, entity.PurposeSquareImage, entity.PurposeChatGIF:
		v = s.media.CheckImageMeta(0, 0, size)
	default:
		return nil
	}
	if v == nil {
		return nil
	}
	log := s.log
	if log == nil {
		log = zap.NewNop()
	}
	log.Warn("upload media size soft-check",
		zap.String("purpose", purpose),
		zap.String("reason", v.Reason),
		zap.Int64("size", v.Size),
		zap.Int64("max_size", v.MaxSize),
	)
	if !s.media.UserReject {
		return nil
	}
	return errs.ErrMediaOversized.WithMsg(i18n.T(reqctx.Lang(ctx), i18n.KeyMediaOversized, nil))
}

func matchSpec(ctx context.Context, in *CreateInput) (entity.Spec, string, error) {
	lang := reqctx.Lang(ctx)
	spec, ok := entity.LookupSpec(in.Purpose)
	if !ok {
		return entity.Spec{}, "", errs.ErrInvalidArgument.WithMsg(i18n.T(lang, i18n.KeyUploadPurposeInvalid, nil))
	}
	mime := entity.NormalizeMIME(in.Mime)
	if _, ok := spec.MIMEs[mime]; !ok {
		return entity.Spec{}, "", errs.ErrInvalidArgument.WithMsg(i18n.T(lang, i18n.KeyUploadMIMEInvalid, nil))
	}
	if in.Size > spec.MaxSize {
		return entity.Spec{}, "", errs.ErrInvalidArgument.WithMsg(i18n.T(lang, i18n.KeyUploadSizeExceeded, nil))
	}
	return spec, mime, nil
}

func (s *Service) readyGroupAvatar(ctx context.Context, userID, groupID int64) error {
	if groupID <= 0 {
		return errs.ErrInvalidArgument.WithMsg(i18n.T(reqctx.Lang(ctx), i18n.KeyUploadGroupRequired, nil))
	}
	if s.groups == nil {
		return nil
	}
	return s.groups.CanSetAvatar(ctx, userID, groupID)
}